Everyone seems to either want, have or use a 3D printer now
a days. I bought my first printer kit in 2012 and I quickly noticed I wanted a
one with more capabilities but since all of the high performance models were so
expensive I designed my own. Eventually I designed a $4,000 printer that I
could sell for $1,400 on KICKSTARTER.

There were a few things that I wanted the
printer to have: two nozzles, Bowden extrusion, enclosed build area, and a
moving xy gantry.

The two nozzles seems like an obvious choice for anyone who
has printed before simply because it allows you to create way more interesting
prints than you could otherwise. For example dissolvable support, multiple
colors and multiple materials (which is pretty cool). I did notice on other
dual nozzle printers, however, that having two big stepper motors created a
massive moving mass so if I wanted any sort of respectable speed I was going to
have to go Bowden style.

Another pet peeve I have is a moving y-axis.
There are big debates on the RepRap IRC and even in the forums about what is
better for the print, a moving Y or Z. I will stand firm on the fact that moving
your print rapidly back and forth is a ridiculous idea. It definitely looks
cool and makes life easier in some regards, but having a variable moving mass
that is semi-molten does not seem like a good idea…

Now that I knew what I wanted to do, I starting creating a
CAD model of the overall design of the printer. This wasn't too difficult just
time consuming. I used V-Slot for my frame and thankfully they have Sketchup
models that anyone can download so it gave me a good starting point.

Once I started building the frame it became quickly apparent
that extrusions require some effort to get them in tight tolerances for a
square frame. This was the process that was recommended by Paul F.

How To Cut 80/20 Extrusions (within 0.002”):

1.Cut the rough dimension with a band saw

2.
Make square first cut on each side using the mill

3.
Bolt an endstop for the extrusion at the required
length to the mill

4.
Cut the first piece. Now that you have an endstop at
the length of your first piece all of the subsequent pieces should be the exact
(or close) length

5.
Take your second piece make a first pass then flip it
butt it up against the endstop and then cut the excess with the mill.

Super square frame on a flat sheet of glass

With my frame done the next step was to create the x and y
axis. This was a little bit difficult because I did not just want to copy
existing printers. I don’t particularly like the Ultimaker’s X/Y set up even
though it does produce great results. I wanted to be a little more creative so
I decided I was going to use my frame as the rails for my Y axis. Since I had
V-slot already I decided to use it for my X-axis. The details were a little
weird to work out, but I think it turned out nicely.

Building the Z-axis was a little bit more
difficult because the print bed was so large and I was concerned about the
print bed bending as a cantilever beam. I eventually settled on a design using
a tri-point mounting system with V-Rails. For the production model, however, I
will change the design to something with less flex. For a production model I
would focus on making the whole z-axis assembly of only 2 or 3 pieces to
minimize play between the interfaces. After using the printer for several
months I think a 4 point mounting system is a better choice because with cyclic
heating and cooling the print bed appears to sag in the corners where it isn't supported.

Laser engraved logo on the side wall. Fun Fact: all the radii in this design are different ratios to pi

With the basic mechanics completed it was time to add the
print bed, nozzles and enclose the printer. The print bed you will notice is
actually white plastic and not glass. This plastic is a plastic from GE called
Ultem 2300 and I thank the delta printer google groups because they were
definitely helpful in brainstorming ideas for a new print surface. Unfortunately
nobody really sells this plastic in small sizes so in small quantities it is
really expensive. However, it is an amazing print surface so far I can say that
it is great for printing PLA, ABS, HIPS, Carbon Fiber, NinjaFlex and LayWood
filament. Nylon really should be printed on Garolite simply because it is
impossible to remove from Ultem (I may have destroyed a couple prints proving
this).

Enclosing the printer was actually pretty interesting
because I got to work with a laser cutter. I laser cut most of the parts based
off of my CAD but I ran into trouble when making the top cover. The Bowden tube
requires a large amount of room so that it doesn’t break the filament or create
too much friction so I need a tall top cover. Initially I made a square box which
was pretty ugly, so I figured it needed to round the edges. My first attempt
was to learn how to bend acrylic and that didn’t turn out so well….

I spent a day trying to get the acrylic to bend at a 90
degree with a 4” radius. Unfortunately I failed pretty hard but that is what
Makerspaces are for, failing and learning!

I did some digging and figured that the best way would be to
make the bend out of acrylic a laser cut living hinge and I think it turned out
pretty well.

The last part and probably the most interesting was the
extruder. I needed an extruder that fit the E3D DMfit connectors and I really wanted it to only have one bolt for
ease of use. Actually, the first one I made was very similar to the makerbot
extruder, without a tensioning screw, but because I am printing in so many
different materials it didn’t work since each material needs a different amount
of idler tension. It took around 4 different prototypes until I finally created
a mechanism that works.

Overall I think the printer turnout splendidly and it makes
some really great prints too. Check out the time lapse of a massive D20 below.
There are also many example prints on www.lathon.net
and the kickstarter . I really enjoyed this project and I
hope I can make LATHON’s for other Makers and engineers because, for us, a 3D
printer is just as important as a hammer.